1. Field of the Invention
This invention relates broadly to liquid chromatography apparatus. More particularly, it concerns devices and methods for making fluid tight connections between rigid and pliable tubes in such apparatus.
2. Description of the Prior Art
In the assembly and operation of liquid chromatography apparatus, it is often necessary to effect or enhance the seal of a connection between a rigid tube and a pliable tube so that the connection will permit fluids under at least modest pressure to be conveyed without leakage through the connected tubes, particular while the apparatus is in full operation. Various devices have been used for this purpose, e.g., tube clamps, cements, binder tapes or straps, etc. This invention provides new, improved methods and devices for making such tubing connections in liquid chromatography apparatus which can involve some special problems as compared to making tubing connections in other environments.
The need to make fluid-tight connections between rigid tubes, e.g., tubes made of metal, and pliable tubes, e.g., tubes made of rubber or plastic, has long existed. Hence, a variety of devices for doing this have been devised and disclosed. For example, it has long been known to use a combination of an internally threaded, tapered compression ring with a circular, externally threaded wedge member to effect a sealed connection between the tubular end of a metal coupling and a rubber hose, see U.S. Pat. No. 36,410.
More recently there has been disclosed a connector for connecting metal pipe to flexible hose by providing a cylindrical protrusion on the pipe supporting an outwardly flared nipple. The hose is placed over the nipple and a sleeve with internal threads is threaded over the hose covering the nipple to tighten the hose on the nipple, see U.S. Pat. No.4,238,132. While a connection of this type may provide an effective pressure seal, its concept of construction is too complicated to be acceptable in the assembly and operation of liquid chromatography apparatus.
In spite of the long time existence of need for pressure tight connections between rigid and pliable tubes and concepts for doing this, including those mentioned above, there has existed a need for uncomplicated, but effective, means to make such connections in liquid chromatography apparatus. Hence, the present invention is directed to the provision of solutions to such need.